An axial flow, gas turbine engine has a compression section, a combustion section and a turbine section. An annular flow path for working medium gases extends axially through the sections of the engine. As the working medium gases are flowed along the annular flow path, the gases are pressurized in the compression section and burned with fuel in the combustion section to add energy to the gases. The hot, pressurized gases are expanded through the turbine section to produce useful work. A portion of the useful work is transferred from the turbine section to the compression section to pressurize the working medium gases.
The engine has a stator assembly for directing the hot working medium gases through the sections of the engine and a rotor assembly for transferring work between the sections of the engine. The rotor assembly in the turbine section includes arrays of rotor blades which extend outwardly across the working medium flow path. The rotor blades have airfoils that are angled with respect to the approaching flow to receive work from the gases and to drive the rotor assembly about the axis of rotation. The stator assembly includes arrays of stator vanes which have airfoils angled with respect to the flow to direct the flow toward the rotor blades of the turbine section. The rotor assembly includes a rotor shaft having an axis of rotation extending axially in the engine to link the turbine rotor blades with associated rotor blades in the compression section. As the turbine rotor blades are driven by the hot gases about the axis of rotation, the rotor shaft drives the rotor blades in the compression section to pressurize the working medium gases.
Because the rotor airfoils and the stator airfoils direct the hot gases in the turbine section, the airfoils are bathed in the gases causing thermal stresses in the blades which can decrease their structural integrity. The first stage rotor blade and first stage stator vane have particularly vulnerable airfoils because the airfoils are close to the combustion section of the engine. In addition, sand or other abrasive particulates are often ingested by the engine and strike the airfoils causing erosion and corrosion of the airfoils even though the airfoils are coated with protective coatings. As a result, it is desirable to inspect the rotor blades and stator vanes at periodic intervals and to replace those blades and vanes which are worn.
It is desirable to inspect other portions of the rotor assembly such as the rotor shaft and the interior of the rotor blade assembly for wear and signs of high stress conditions. Like inspections of the rotor blades and stator vanes, such inspections may be difficult and time consuming to conduct if construction of the rotor assembly does not lend itself to simple disassembly or requires extensive fixturing to support the rotating parts with respect to the stationary parts.
Accordingly scientists and engineers are working to develop gas turbine engine constructions and methods of disassembling gas turbine engines which permit modular disassembly of portions of the rotor assembly to simplify disassembly and to reduce the need for fixturing the parts of the rotor assembly.